Step-by-step feed gear



STEP-BY-STEP FEED GEAR Filed Sept. 20, 1968 Fig. 1

BY ATTYS.

United States Patent I 3,529,485 STEP-BY-STEP FEED GEAR RainerKiitferlein, Munich-Solln, Germany, assignor to SiemensAktiengesellschaft, Erlangen, Germany, a corporation of Germany FiledSept. 20, 1968, Ser. No. 761,195 Claims priority, application Germany,Sept. 29, 1967,

83 Int. Cl. F16h 27/64, 35/02, 37/12 U.S. Cl. 74394 6 Claims ABSTRACT OFTHE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention Thisinvention relates in general to step-by-step feed mechanisms such as,for example, for feeding cards or tapes through recording devices.Modern data feeding and discharging equipment requires high-speedprocessing apparatus. Particularly in printing and punching units withstep-by-step feed the increasing speed has caused difficulties becauseof the alternate acceleration and deceleration operations. This hasrequired that the masses of th accelerated and decelerated parts he madeas small as possible.

Description of the prior art Step-by-step feed gears have been known inwhich a planetary wheel is put into oscillatory movement around aprincipal gear axis. An oscillating movement is superimposed over theuniformly developing hob gear movement in the planetary gear so that thespeeds of both movements add up at certain times to zero at the output.The oscillating movement of the planetary wheel is generated by a curvedrive whose curve may be designed as desired within wide limits.

Although in such gears the masses which are moved at non-uniform ratesare relatively small in relation to the step-by-step feed gears, thereis still a considerable oscillating mass due to the arm that oscillatesthe planetary wheel.

Further efforts were made to obtain oscillating movement to besuperimposed over the uniform movement from gear parts moved asuniformly as possible. This led to an additionally proposed step-by-stepfeed gear, characterized by a gear with a rotating part, whereby anoscillating movement is caused on the output which is large enough tocompensate at certain times for the otherwise uniform movement. Anadditional gear generates on the output side an additional movement ofcomparatively low amplitude which is used to counteract to a substantialextent for the deviations of the object to be moved from a restingposition.

Although rather good results were obtained with such step-by-step feedgears, they are very expensive.

3,529,485 Patented Sept. 22, 1970 SUMMARY OF THE INVENTION The presentinvention relates to an intermittent drive of the step-by-step feed geartype which has very few parts and in which the output rotates in amultiplicity of steps as desired and which is usable for high stepfrequencies as, for example, between to 200 steps per second. A rockerarm is mounted on the output shaft and follows a curved disk whichrotates around a support shaft mounted eccentrically in a rotating disk.A sprocket gear is mounted on the shaft which supports the curved diskand engages a fixed sprocket wheel which engages the other sprocketwheel thereby causing the curved disk to rotate. A drive shaft iscoupled to the rotating disk to drive it. The structure results in astep-by-step feed gear which has very few parts and in which only thedriven shaft with the rocker arm must be accelerated and decelerated.The remaining parts of the structure rotate at uniform speeds and thusmay be designed with a substantial mass since they do not have to becontinuously accelerated and decelerated.

The step-by-step gear, according to the invention, can be designedalmost free from play and is appropriate for high step frequencies.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of certainpreferred embodiments thereof taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the step-by-stepgear arrangement according to this invention; and

FIG. 2 is a graph illustrating the sequence of movements in thestep-by-step gear arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a supportingplate 5 to which is nonrotatably attached a sun gear 6. The planet gear3 engages the sun gear 6 and is supported on a shaft 2 which extendsthrough a disk gear 1. The shaft 2 is rotatably supported in the diskgear 1 by the bushing 9 and carries a cam 4 on the opposite side of thedisk gear 1. The drive shaft 10 carries a drive gear 12 which mesheswith the teeth of the disk gear 1 to drive it. A driven shaft 8 carriesa rocker arm member 7 which has a cam follower 13 that engages thesurface of the cam 4. A pin 14 is mounted on the disk gear 1 and aspring 11 extends between the pin 14 and the lever arm 7 to bias thelever arm toward the cam surface 4.

The driving shaft 10 rotates the gear 12 which in turn causes the diskgear 1 to rotate. As the disk gear rotates relative to the plate 5, thesun gear 6, which is nonrotatably connected to the plate 5, drives theplanet gear 3 thus rotating the shaft 2. The shaft 2 drives the cam 4and the cam 4 causes the cam follower 13 of the rocker arm 7 to move,thus driving the output shaft 8.

The shaft 10 and disk gear 1 and shaft 2 and planet gear 3 and cam 4 maybe rotated at a constant angular velocity and only the crank arm 7 andthe output shaft 8 will be driven in step fashion.

Thus, the parts of the step-by-step feed mechanism may be maderelatively heavy except for the rocker arm 7. This is because theremaining parts of the apparatus rotate with a fixed velocity. It is tobe understood that the axis of rotation of the driven shaft 8 coincideswith the axis of rotation of the disk gear 1. The disk gear 1 is mountedconcentrically with the sun gear 6.

FIG. 2 illustrates the step motion obtainable with the mechanism ofFIG. 1. The curve A illustrates the motion of the disk gear 1 as afunction of time as it rotates at a fixed velocity. The oscillatingmovement caused by the cam 4 is illustrated by curve B in FIG. 2. Themovements of curves A and B are added and result when the cam 4 has anappropriate shape to the desired step movement of the driven shaft 8.This is illustrated by the curve A plus B in FIG. 2 which shows themovement of the driven shaft 8 as a function of time. The only lostmotion which would occur in the structure would be between the cam shaft2 and the disk gear 1 and the planet gear 3 and the sun gear 6. This canbe substantially reduced by the eccentric bushing 9 in which the shaft 2is mounted.

The structure of FIG. 1 requires only that the driven shaft 8 and rockerarm 7 be accelerated and decelerated and the remaining moving part ofthe structure rotate at uniform speed. They may therefore be designedrelatively heavy and may act as a gyrating mass.

Although the cam surface 4 and the cam follower 14 are shown as springloaded, it is to be realized that the cam 4 could be formed with agroove in which the cam follower rode to obtain intermittentstep-by-step motion of the shaft 8.

A further embodiment of the step-by-step gear mechanism may be obtainedby rotating the sun gear 6 relative to the plate 5 to add its motion.This would result in a variation of the magnitude of the step-by-stepfeed in a simple manner.

Although various minor modifications might be suggested by those versedin the art, it should be understood that I wish to embody all suchmodifications as reasonably and properly come within the scope of mycontribution to the art.

I claim as my invention:

1. A step-by-step feed gear mechanism for a driven shaft comprising,

two parts coupled to each other, one of which would by itself cause auniform feed motion and the second part coupled to the first part to addan oscillating movement so that the driven shaft is accelerated anddecelerated comprising,

a rocker arm mounted on the driven shaft.

a rotating disk gear,

a cam engageable with said rocker arm and said cam mounted on a camshaft for rotary motion,

the cam shaft eccentrically mounted in said disk gear,

a planet gear mounted on the cam shaft, and

a sun gear concentrically mounted relative to the disk gear and engagedby the planet gear and causing rotation of the cam, and

said cam also rotating with its shaft on a circular orbit around theaxis of the driven shaft.

2. A step-by-step feed gear mechanism according to claim 1, whereby therocker arm engages the cam in the area of the circular orbit describedby the axis of the cam.

3. A step-by-step feed gear mechanism according to claim 2 whereby therocker arm is spring biased in engagement with the cam.

4. A step-by-step gear mechanism according to claim 1 whereby the sungear is stationary.

5. A step-by-step gear mechanism according to claim 1 comprising adriving shaft and whereby the disk gear is driven by the driving shaft.

6. A step-by-step gear mechanism according to claim 5 wherein a drivinggear is mounted on the driving shaft and the disk gear is formed withgear teeth which mesh with the driving gear.

References Cited UNITED STATES PATENTS 2,845,808 8/1958 Stover 74-3942,861,672 11/1958 Buehrer et a1. 3,076,351 2/1963 Moss 74-394 OTHERREFERENCES Mathurin, E. L. and Wooding, E.R.: Epicyclic IncrementalMotion Mechanism.

In IBM Technical Disclosure Bulletin 4(2), p. 4, July 1961.

LEONARD H. GERIN, Primary Examiner U.S. Cl. X.R. 74-52, 84

